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The short answer: almost every US portable space heater draws 1,500 watts on high and 750 watts on low. At 120 volts that is 12.5 amps, and 1,500 watts is the practical ceiling for anything plugged into a standard household outlet. Running cost is about 26 cents an hour at the US average residential rate of roughly 17 cents per kWh (EIA), or 13 cents on the low setting. The heater type — ceramic, infrared, oil-filled, fan-forced — does not change either number.
We do not physically handle the products we rank; picks come from aggregated owner reviews and expert consensus — see how we rank. Model shortlists are in best space heater.
Does the heater type change the wattage?
No, and this is the single most misunderstood point about electric heating. Ceramic, infrared, quartz, mica-panel and oil-filled heaters are all resistive: they convert essentially 100 percent of the electricity they consume into heat in the room. A 1,500-watt infrared heater and a 1,500-watt oil-filled radiator produce identical heat and identical cost per hour. Marketing claims that one type is inherently cheaper to run describe how the heat feels, not what it costs.
| Heater type | Typical watts | Amps at 120 V | Cost per hour at 17¢/kWh | Best suited to |
|---|---|---|---|---|
| Ceramic fan-forced | 750 / 1,500 W | 6.3 / 12.5 A | $0.13 / $0.26 | Enclosed rooms, fast warm-up |
| Infrared / quartz | 1,000 – 1,500 W | 8.3 – 12.5 A | $0.17 – $0.26 | Garages, drafty or large spaces |
| Oil-filled radiator | 600 / 900 / 1,500 W | 5.0 / 7.5 / 12.5 A | $0.10 / $0.15 / $0.26 | Bedrooms, silent steady heat |
| Micathermic panel | 1,500 W | 12.5 A | $0.26 | Slim placement, quiet operation |
| Small personal / desk | 200 – 400 W | 1.7 – 3.3 A | $0.03 – $0.07 | Under a desk, one person |
| Garage 240 V hardwired | 3,000 – 5,000 W | 12.5 – 20.8 A at 240 V | $0.51 – $0.85 | Workshops, dedicated circuit |
The comparison that does matter is delivery. Infrared warms surfaces in its path immediately, which is why it wins in a garage where heating the air is pointless. Ceramic circulates warm air and suits a closed room. Oil-filled is silent and holds warmth after switching off, which suits bedrooms. The full trade-offs are in ceramic vs infrared and oil-filled vs ceramic.
What circuit does a 1,500-watt heater need?
Effectively a 15-amp circuit to itself, or a 20-amp circuit shared lightly. The 12.5-amp draw sits above the NEC continuous-load allowance of 12 amps for a 15-amp breaker, so a heater plus a vacuum, a hair dryer or a second heater on the same circuit will trip the breaker — and a breaker doing that is working correctly, not being fussy.
- Direct to a wall outlet. No extension cords, power strips, surge protectors or plug-in timers, per CPSC guidance.
- Check the outlet temperature. A plug or receptacle that is warm to the touch, discolored, or smells hot means a loose connection — stop using it and call an electrician.
- Nothing else significant on the breaker. Bedroom and living-room receptacles are often chained across several rooms.
- Do not upsize the breaker. The breaker protects the wire, not the appliance. Persistent tripping is diagnosed in why does my space heater trip the breaker.
What does that add to the bill?
Run it 8 hours a day for a month on high and a 1,500-watt heater uses 360 kWh — about $61 at 17 cents per kWh, or over $100 in high-rate states like California and much of New England. Used the way most people actually use one, a few hours in the evening in a single room, it is closer to $20 to $30 a month. A working thermostat changes this more than anything else, because the element only draws power while it is on.
Sizing the heater to the room is the other lever — an undersized unit runs continuously and never satisfies. That math is in what size space heater for a room, larger spaces are covered in best space heater for a large room, and an eight-hour cost breakdown is in running cost for 8 hours. On overnight use, read are space heaters safe to leave on overnight first.